A student riding a bicycle on a $5 \mathrm{~km}$ one-way street takes 40 minutes to reach home. The student stopped for 15 minutes during this ride. 60 vehicles overtook the student (assume the number of vehicles overtaken by the student is zero) during the ride and 45 vehicles while the student stopped. The speed of vehicle stream on that road (in $\mathrm{km} / \mathrm{hr}$ ) is
(A) 7.5
(B) 12
(C) 40
(D) 60
A student riding a bicycle on a $5 \mathrm{~km}$ one-way street takes 40 minutes to reach home. The student stopped for 15 minutes during this ride. 60 vehicles overtook the student (assume the number of vehicles overtaken by the student is zero) during the ride and 45 vehicles while the student stopped. The speed of vehicle stream on that road (in $\mathrm{km} / \mathrm{hr}$ ) is
(A) 7.5
(B) 12
(C) 40
(D) 60